The present invention relates to a method of ultrasonic imaging and an ultrasonic diagnostic apparatus, and more particularly to a method of ultrasonic imaging and an ultrasonic diagnostic apparatus capable of producing ultrasonic images by which it is possible to visually recognize at a glance the time-wise change of a blood flow.
In obtaining an ultrasonic image of a blood flow, there has been a convention to use small bubbles in blood as the contrast agent. These small bubbles disperse by being hit by a strong ultrasonic wave.
On this account, after the imaging for a high-transmission frame (a frame taken by use of an ultrasonic wave which is strong enough to disperse the contrast agent), imaging for low-transmission frames (frames taken by use of an ultrasonic wave which is not so strong as to disperse the contrast agent) is carried out continuously, and imaging for another high-transmission frame is carried out on expiration of the time at which the view field is filled with a blood flow including the contrast agent, with these operations being implemented cyclically, as shown in FIG. 1.
In FIG. 1, vertical line segments aligning along the time axis represent transmission time points and transmission strengths of sonic beams which form the frames.
FIG. 2(a) shows sonic beams which form a high-transmission frame, and the bold lines signify an ultrasonic wave which is strong enough to disperse the contrast agent. Indicated by V is a blood vessel, and the arrow indicates the direction of blood flow.
In contrast, FIG. 2(b) shows sonic beams which form a low-transmission frame, and the thin lines signify an ultrasonic wave which is not so strong as to disperse the contrast agent.
It has been possible to view the state of a blood flow at one moment in the image of a high-transmission frame which is taken based on the above-mentioned conventional scheme.
However, this scheme has been problematic in that it cannot provide a view of the time-wise change of a blood flow. Specifically, if it is intended to view the time-wise change of a blood flow, it is necessary to compare images of high-transmission frames taken at different time points, and it necessitates skill.
It is an object of the present invention to provide a method of ultrasonic imaging and an ultrasonic diagnostic apparatus capable of producing ultrasonic images by which it is possible to visually recognize at a glance the time-wise change of a blood flow.
At a first viewpoint, the present invention provides a method of ultrasonic imaging which is characterized by transmitting an ultrasonic wave at such a strength as to disperse the contrast agent for part of a number of sonic beams which form one frame and transmitting an ultrasonic wave at such a strength as not to disperse the contrast agent for other sonic beams, and producing an image for one frame from received signals which correspond to the ultrasonic wave transmission.
In the ultrasonic imaging method of the first viewpoint, the contrast agent in one part of the image disperses, while the contrast agent in other part does not disperse. Therefore, when another imaging takes place after such a time length that the flow range is present within the view field, the portion with the contrast agent being dispersed moves slightly in its position on the image. When this operation is repeated for a flow which intersects the direction of sonic beam, an effect similar to the tagging in magnetic resonance imaging emerges, and the flow seems to have a stripe pattern indicative of the passing time. As a result, it becomes possible to visually recognize the time-wise change of a blood flow at a glance.
At a second viewpoint, the present invention provides a method of ultrasonic imaging which is characterized by transmitting an ultrasonic wave at such a strength as not to disperse the contrast agent for all of a number of sonic beams which form one frame, producing an image for one frame from received signals which correspond to the ultrasonic wave transmission, and interposing the formed frame between frames which are produced by the ultrasonic imaging method mentioned in the first viewpoint.
In the ultrasonic imaging method of the second viewpoint, a frame without the dispersion of contrast agent is interposed between frames with the dispersion of contrast agent in part of the image, whereby the real-time property of progressive imaging can be improved.
At a third viewpoint, the present invention provides a method of ultrasonic imaging which is derived from the method of the second viewpoint, and is characterized in that one timing of ultrasonic wave transmission for one frame at such a strength as to disperse the contrast agent and another timing of ultrasonic wave transmission for a later frame at such a strength as to disperse the contrast agent have a time difference which is based on the heart beat.
In the ultrasonic imaging method of the third viewpoint, there is provided a time difference between events of transmission by which the contrast agent is dispersed in part of the image, whereby a pulsing flow can be observed properly.
At a fourth viewpoint, the present invention provides a method of ultrasonic imaging which is derived from the method of the third viewpoint, and is characterized in that there are in one frame at least two spaced-out sonic beams for which an ultrasonic wave is transmitted at such a strength as to disperse the contrast agent.
In the ultrasonic imaging method of the fourth viewpoint, the contrast agent disperses at least two spaced-out positions, whereby a number of stripe patterns can be appended to a flow at the same time.
At a fifth viewpoint, the present invention provides a method of ultrasonic imaging which is characterized by transmitting an ultrasonic wave at such a strength as to disperse the contrast agent for a certain depth of a number of sonic beams which form one frame or a certain depth seen from the ultrasonic probe and transmitting an ultrasonic wave at such a strength as not to disperse the contrast agent for other depths, and producing an image for one frame from received signals which correspond to the ultrasonic wave transmission.
In the ultrasonic imaging method of the fifth viewpoint, the contrast agent in one part of the image disperses, whereas the contrast agent in other part does not disperse. Therefore, when another imaging takes place after such a time length that the flow range is present within the view field, the portion with the contrast agent being dispersed moves slightly in its position on the image. When this operation is repeated for a flow which intersects the direction of sonic beam, an effect similar to the tagging in magnetic resonance imaging emerges, and the flow seems to have a stripe pattern indicative of the passing time. Whereby, it becomes possible to visually recognize at a glance the time-wise change of a blood flow.
At a sixth viewpoint, the present invention provides a method of ultrasonic imaging which is characterized by transmitting an ultrasonic wave at such a strength as not to disperse the contrast agent for all of a number of sonic beams which form one frame, producing an image for one frame from received signals which correspond to the ultrasonic wave transmission, and interposing the formed frame between frames which are produced by the ultrasonic imaging method mentioned in the fifth viewpoint.
In the ultrasonic imaging method of the sixth viewpoint, a frame without the dispersion of contrast agent is interposed between frames with the dispersion of contrast agent in part of the image, whereby the real-time property of progressive imaging can be improved.
At a seventh viewpoint, the present invention provides a method of ultrasonic imaging which is derived from the method of the sixth viewpoint, and is characterized in that one timing of ultrasonic wave transmission for one frame at such a strength as to disperse the contrast agent and another timing of ultrasonic wave transmission for a later frame at such a strength as to disperse the contrast agent have a time difference which is based on the heart beat.
In the ultrasonic imaging method of the seventh viewpoint, there is provided a time difference between events of transmission by which the contrast agent is dispersed in part of the image, whereby a pulsing flow can be observed properly.
At an eighth viewpoint, the present invention provides a method of ultrasonic imaging which is derived from the method of the seventh viewpoint, and is characterized in that there are in one frame at least two spaced-out positions of depths for which an ultrasonic wave is transmitted at such a strength as to disperse the contrast agent.
In the ultrasonic imaging method of the eighth viewpoint, the contrast agent disperses at least two spaced-out positions, whereby a number of stripe patterns can be appended to the flow at the same time.
At a ninth viewpoint, the present invention provides a method of ultrasonic imaging characterized by combining an ultrasonic imaging method of the first through fourth viewpoints and an ultrasonic imaging method of the fifth through eighth viewpoints.
In the ultrasonic imaging method of the ninth viewpoint, stripe patterns are appended to both of a flow which intersects the direction of sonic beam and a flow which is virtually parallel to the direction of sonic beam, whereby it is particularly suitable to observe a two-dimensional flow of the cardiac ventricle and atrium.
At a tenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus characterized by comprising an ultrasonic probe, a transmission/reception means which transmits an ultrasonic wave from the ultrasonic probe and receives a signal which corresponds to the ultrasonic wave transmission, a transmission strength control means which controls the ultrasonic wave transmission to have such a strength as to disperse the contrast agent for part of a number of sonic beams which form one frame and have such a strength as not to disperse the contrast agent for other sonic beams, and an image producing means which produces an image for one frame from the received signals.
The ultrasonic diagnostic apparatus of the tenth viewpoint can suitably carry out the ultrasonic imaging method of the first viewpoint.
At an eleventh viewpoint, the present invention provides an ultrasonic diagnostic apparatus which is derived from the apparatus of the tenth viewpoint and is characterized in that the transmission strength control means controls the ultrasonic wave transmission such that one frame, which is formed at such a strength as not to disperse the contrast agent for all of a number of sonic beams which form one frame, is interposed between frames which are formed by the ultrasonic wave transmission at such a strength as to disperse the contrast agent for part of a number of sonic beams which form one frame and the ultrasonic wave transmission at such a strength as not to disperse the contrast agent for other sonic beams.
The ultrasonic diagnostic apparatus of the eleventh viewpoint can suitably carry out the ultrasonic imaging method of the second viewpoint.
At an twelfth viewpoint, the present invention provides an ultrasonic diagnostic apparatus which is derived from the apparatus of the eleventh viewpoint and is characterized in that the transmission strength control means controls the ultrasonic wave transmission such that one timing of ultrasonic wave transmission for one frame at such a strength as to disperse the contrast agent and another timing of ultrasonic wave transmission for a later frame at such a strength as to disperse the contrast agent have a time difference which is based on the heart beat.
The ultrasonic diagnostic apparatus of the twelfth viewpoint can suitably carry out the ultrasonic imaging method of the third viewpoint.
At a thirteenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus which is derived from an apparatus of the tenth through twelfth viewpoints and is characterized in that the transmission strength control means controls the ultrasonic wave transmission such that there are in one frame at least two spaced-out sonic beams for which an ultrasonic wave is transmitted at such a strength as to disperse the contrast agent.
The ultrasonic diagnostic apparatus of the thirteenth viewpoint can suitably carry out the ultrasonic imaging method of the fourth viewpoint.
At a fourteenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus characterized by comprising an ultrasonic probe, a transmission/reception means which transmits an ultrasonic wave from the ultrasonic probe and receives a signal which corresponds to the ultrasonic wave transmission, a transmission strength control means which controls the ultrasonic wave transmission to have such a strength as to disperse the contrast agent for a certain depth of a number of sonic beams which form one frame or a certain depth seen from the ultrasonic probe and have such a strength as not to disperse the contrast agent for other depths, and an image producing means which produces an image for one frame from the received signals.
The ultrasonic diagnostic apparatus of the fourteenth viewpoint can suitably carry out the ultrasonic imaging method of the fifth viewpoint.
At a fifteenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus which is derived from the apparatus of the fourteenth viewpoint and is characterized in that the transmission strength control means controls the ultrasonic wave transmission such that one frame, which is formed by the ultrasonic wave transmission at such a strength as not to disperse the contrast agent for all of a number of sonic beams which form one frame, is interposed between frames which are formed by the ultrasonic wave transmission at such a strength as to disperse the contrast agent for a certain depth of a number of sonic beams which form one frame or a certain depth seen from the ultrasonic probe and at such a strength as not to disperse the contrast agent for other depths.
The ultrasonic diagnostic apparatus of the fifteenth viewpoint can suitably carry out the ultrasonic imaging method of the sixth viewpoint.
At a sixteenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus which is derived from the apparatus of the fifteenth viewpoint and is characterized in that the transmission strength control means controls the ultrasonic wave transmission such that one timing of ultrasonic wave transmission for one frame at such a strength as to disperse the contrast agent and another timing of ultrasonic wave transmission for a later frame at such a strength as to disperse the contrast agent have a time difference which is based on the heart beat.
The ultrasonic diagnostic apparatus of the sixteenth viewpoint can suitably carry out the ultrasonic imaging method of the seventh viewpoint.
At a seventeenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus which is derived from an apparatus of the fourteenth through sixteenth viewpoints and is characterized in that the transmission strength control means controls the ultrasonic wave transmission such that there are in one frame at least two spaced-out positions of depths for which an ultrasonic wave is transmitted at such a strength as to disperse the contrast agent.
The ultrasonic diagnostic apparatus of the seventeenth viewpoint can suitably carry out the ultrasonic imaging method of the eighth viewpoint.
At an eighteenth viewpoint, the present invention provides an ultrasonic diagnostic apparatus characterized by comprising an ultrasonic probe, a transmission/reception means which transmits an ultrasonic wave from the ultrasonic probe and receives a signal which corresponds to the ultrasonic wave transmission, a transmission strength control means which controls the ultrasonic wave transmission to have such a strength as to disperse the contrast agent for part of a number of sonic beams which form one frame and have for other sonic beams such a strength as to disperse the contrast agent for a certain depth of the sonic beams or a certain depth seen from the ultrasonic probe and have such a strength as not to disperse the contrast agent for other depths, and an image producing means which produces an image for one frame from the received signals.
The ultrasonic diagnostic apparatus of the eighteenth viewpoint can suitably carry out the ultrasonic imaging method of the ninth viewpoint.
According to the ultrasonic imaging method and ultrasonic diagnostic apparatus of this invention, which actively utilize the dispersion of contrast agent in the presence of a strong ultrasonic wave, it is possible to produce ultrasonic images which enable to visually recognize at a glance the time-wise change of a blood flow.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.